Originally a vassal of Sosso, in the 1230s they started to rebel. Mali, rich thanks to gold and salt, became the most prominent of Sosso's ex-vassals.
In 1240, Sundiata Keita of the Mandinka people defeated Sosso king Sumanguru Kante, the murderer of his father and eleven brothers, at the battle of Kirina. After that, he converted to Islam.
Following this victory, Sundiata expanded his Empire to include most of the important parts of West Africa, including the towns of Walata, Tadmekka, and Gao at the southern end of the desert trade routes. The Mali Empire was made up of 3 allied states and 12 tributaries. The three states were Mali (which held the capital of the Empire, Niani), Mema, and Wagadou, the former Ghana Empire. The 12 tributaries were referred to as the 12 doors of Mali to which only the Mansa (emperor) held the key. They were Djebeda, Tabon, Negueboria, Kankigne, Togom, Sili, Krina, Koulikoro, Diaghan, Kita, Ka-ba, and Do.
In 1255, Sundiata died, to be succeeded by his son Mansa Wali Keita. During his reign, he made Hajj. 1270, Mansa Wali Keita died too.
In the year of 1285, after three weak Mansas, the general and former slave Sakura seized control of Mali. 1300, he was killed near Tripoli.
During 1312-37, Kango / Kankan Musa reigned in Mali, at its height of power. Under him, in 1324 the Mali Empire gained direct control over the city of Timbuktu. Mansa Musa made Hajj in the same year; when he passed through Cairo in July, he was accompanied by five hundred slaves, each reportedly carrying a six-pound staff of gold. He spent out so much gold that it took 12 years for the economy to recover, due to the rapid inflation that it had initiated. In 1325, Musa returned from hajj; the Sankore Masjid in Timbuktu had been converted into a fully staffed Madrassa (Islamic school, or in this case university) meanwhile, having the largest collections of books in Africa since the Library of Alexandria, financed by a royal lady.
In 1360, a Civil War took place in Mali.
Since ~1400, the Power of the Mali Empire began to crumble, as its former vassals (like Songhay / Gao) gained more power.